TORONTO -- Canada's busiest airport says operations are back to normal after U.S. Customs and Border Protection experienced "nationwide technical issues" Monday morning.

Toronto Pearson International Airport says the issues with the American authority's customs kiosks, which left border agents processing travellers manually, were resolved.

A spokesman for the airport says the Canadian Air Transport Security Authority decided to pause pre-clearance for passengers travelling to the U.S. in Terminal 1, so as not to overcrowd the customs area while the systems were down.

The airport says pre-clearance has resumed now that the issues have been resolved.